Activation of ERM proteins in vivo by Rho involves phosphatidyl-inositol 4-phosphate 5-kinase and not ROCK kinases

摘要: When activated, ERM (ezrin, radixin, moesin) proteins are recruited to the plasma membrane, with concomitant carboxy-terminal threonine phosphorylation, where they crosslink actin filaments membrane form microvilli (reviewed in [1] [2] [3] [4] [5]). Here, we report that, when NIH3T3 or HeLa cells were transfected a constitutively active mutant of small GTPase RhoA (V14RhoA), induced and level threonine-phosphorylated (CPERM) [6] [7] increased approximately 30-fold. This increase was not observed following transfection forms two other Rho-family GTPases, Rac1 Cdc42, direct effector Rho, Rho-kinase (also known as ROKalpha ROCK-II) [8] [9] [10]. The V14RhoA-induced phosphorylation suppressed by Y-27632, specific inhibitor ROCK kinases including [11]. Overexpression another phosphatidylinositol 4-phosphate 5-kinase (PI4P5K) type Ialpha [12] [13] [14], but kinase-inactive [15], sixfold CPERM, microvilli. Together previous finding that PI4P5K product 4,5-bisphosphate (PIP(2)) activates vitro [16], our data suggest PIP(2), kinases, is involved RhoA-dependent activation vivo. state maintained through yet undetermined leading microvillus formation.